/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.master;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;

import org.apache.hadoop.hbase.NamespaceDescriptor;
import org.apache.hadoop.hbase.NamespaceNotFoundException;
import org.apache.hadoop.hbase.ServiceNotRunningException;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hadoop.hbase.master.procedure.CreateNamespaceProcedure;
import org.apache.hadoop.hbase.master.procedure.DeleteNamespaceProcedure;
import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
import org.apache.hadoop.hbase.master.procedure.ModifyNamespaceProcedure;
import org.apache.hadoop.hbase.master.procedure.ProcedurePrepareLatch;
import org.apache.hadoop.hbase.procedure2.Procedure;
import org.apache.hadoop.hbase.procedure2.ProcedureExecutor;
import org.apache.hbase.thirdparty.com.google.common.util.concurrent.AbstractService;
import org.apache.hadoop.hbase.util.NonceKey;

@InterfaceAudience.Private
class ClusterSchemaServiceImpl extends AbstractService implements ClusterSchemaService {
    private final TableNamespaceManager tableNamespaceManager;
    private final MasterServices masterServices;
    private final static List<NamespaceDescriptor> EMPTY_NAMESPACE_LIST = Collections.unmodifiableList(new ArrayList<NamespaceDescriptor>(0));

    ClusterSchemaServiceImpl(final MasterServices masterServices) {
        this.masterServices = masterServices;
        this.tableNamespaceManager = new TableNamespaceManager(masterServices);
    }

    // All below are synchronized so consistent view on whether running or not.


    private synchronized void checkIsRunning() throws ServiceNotRunningException {
        if(!isRunning())
            throw new ServiceNotRunningException();
    }

    @Override
    protected synchronized void doStart() {
        try {
            notifyStarted();
            this.tableNamespaceManager.start();
        } catch(IOException ioe) {
            notifyFailed(ioe);
        }
    }

    @Override
    protected void doStop() {
        // This is no stop for the table manager.
        notifyStopped();
        TableNamespaceManager tnsm = getTableNamespaceManager();
        if(tnsm != null) {
            tnsm.stop("Stopping");
        }
    }

    @Override
    public TableNamespaceManager getTableNamespaceManager() {
        return this.tableNamespaceManager;
    }

    private long submitProcedure(final Procedure<MasterProcedureEnv> procedure, final NonceKey nonceKey) throws ServiceNotRunningException {
        checkIsRunning();
        ProcedureExecutor<MasterProcedureEnv> pe = this.masterServices.getMasterProcedureExecutor();
        return pe.submitProcedure(procedure, nonceKey);
    }

    @Override
    public long createNamespace(NamespaceDescriptor namespaceDescriptor, final NonceKey nonceKey,
            final ProcedurePrepareLatch latch) throws IOException {
        return submitProcedure(
                new CreateNamespaceProcedure(this.masterServices.getMasterProcedureExecutor().getEnvironment(), namespaceDescriptor, latch),
                nonceKey);
    }

    @Override
    public long modifyNamespace(NamespaceDescriptor namespaceDescriptor, final NonceKey nonceKey,
            final ProcedurePrepareLatch latch) throws IOException {
        return submitProcedure(
                new ModifyNamespaceProcedure(this.masterServices.getMasterProcedureExecutor().getEnvironment(), namespaceDescriptor, latch),
                nonceKey);
    }

    @Override
    public long deleteNamespace(String name, final NonceKey nonceKey, final ProcedurePrepareLatch latch) throws IOException {
        return submitProcedure(new DeleteNamespaceProcedure(this.masterServices.getMasterProcedureExecutor().getEnvironment(), name, latch),
                nonceKey);
    }

    @Override
    public NamespaceDescriptor getNamespace(String name) throws IOException {
        NamespaceDescriptor nsd = getTableNamespaceManager().get(name);
        if(nsd == null)
            throw new NamespaceNotFoundException(name);
        return nsd;
    }

    @Override
    public List<NamespaceDescriptor> getNamespaces() throws IOException {
        checkIsRunning();
        Set<NamespaceDescriptor> set = getTableNamespaceManager().list();
        if(set == null || set.isEmpty())
            return EMPTY_NAMESPACE_LIST;
        List<NamespaceDescriptor> list = new ArrayList<>(set.size());
        list.addAll(set);
        return Collections.unmodifiableList(list);
    }
}
